1. Field of the Invention
The present invention relates to a magneto-generator that generates an electric power by the action of electromagnetic induction between a magnet and a magneto coil due to the rotation of a flywheel.
2. Description of the Related Art
FIGS. 12 and 13 show a rotor of a conventional flywheel-shaped magneto-generator disclosed in the Japanese Patent Publication (unexamined) No, 101630/2002. FIG. 12 is a cross sectional view of the magneto-generator, and FIG. 13 is a longitudinal section view taken along the line A—A of FIG. 12. In the drawings, reference numeral 1 designates a bowl-shaped flywheel formed of a circumferential wall 1c, a sidewall 1d on the side of one end of the circumferential wall 1c, and an opening 1e on the other end side. Numeral 2 designates a plurality of magnets mounted onto the circumferential wall 1c of the flywheel 1. These magnets 2 engage with protrusions 1a provided circumferentially on the inside of the circumferential wall 1c. Numeral 3 designates a tubular guard ring that is annularly mounted in close contact with the inside of the magnet 2. This guard ring 3 is formed by drawing of a metal plate, and includes a flange part 3a that is formed by bending at one end.
Numeral 4 designates a resin that fixes the magnet 2 and the guard ring 3 to the flywheel 1, thus forming an integral whole. This resin 4 is filled in between both sides of the magnet 2 and between ends of each magnet 2. Numeral 5 designates a boss part for mounting onto a rotary shaft (not shown). This rotary shaft 5 is fixed to a central portion of the sidewall 1d of the flywheel 1. Numeral 4a designates fins provided on the inside of the sidewall 1d of the flywheel 1. Numeral 1b designates a shoulder that is formed by extrusion molding on the inside of the circumferential wall 1c at several points of the entire circumference of the flywheel 1.
Describing the operations of the aforementioned conventional flywheel-shaped magneto-generator, by the rotation of the rotary shaft, the boss part 5 and the flywheel 1 that are attached to the rotary shaft rotate. Then, the fins 4a that are provided on the inside of the sidewall 1d of the flywheel 1 agitate gas in an air gap between a magneto coil and the sidewall 1d of the flywheel 1, thereby cooling the magneto coil.
In the field of a magneto-generator, it is a recent trend that further downsizing and higher power are needed. As an effective way to meet such needs, the air gap between the magneto coil and the flywheel 1 is made to be smaller so that magnetic flux from the magnet 2 is efficiently transmitted to the magneto coil.